Developing apparatus with a heated transport roll



G. N. ALSETH April 22, 19 9 Sheet of2 Filed Sept. 29, 1967 I April 22, 1 969 G. N.- ALSETH DEVELOPING APPARATUS WITH A HEATED TRANSPORT ROLL Filed Sept. 29. 1967 Sheet fNVENTOR. GILMOfiE/YflLSL-TH ram/H:

United States Patent 3,439,905 DEVELOPING APPARATUS WITH A HEATED TRANSPORT ROLL Gilmore Noble, Alseth, Minneapolis, Minn., assignor to Minnesota Mining and Manufacturing Company, St.

Paul, Minn., a corporation of Delaware Filed Sept. 29, 1967, Ser. No. 671,814 Int. Cl. F27b 9/28; G01d 15/10; G03d 13/00 US. Cl. 263-6 8 Claims ABSTRACT OF THE DISCLOSURE A developing apparatus for use in the development of an image on a film or paper support material of various sizes by the application of heat to one surface of the material. The apparatus comprising a uniformly heated roll with means for applying subatmospheric pressure to openings in said roll to draw said support into contact with the roll surface and for transporting the support about said roll from an inlet area to a discharge area for the development of an image on said support while in contact with said heated roll.

This invention relates to equipment for the development of images on a support material such as film or paper of various sizes and in one aspect relates to a unit for developing a fragile photosensitive heat-developable coating on one surface of a said material which unit permits the material to be readily fed into and discharged from the machine without damage to the coating.

Previously, devices for heat development of images on various supporting surfaces have all utilized a guide or driven belt to maintain thesupporting material in contact with a rotatable drum, roller or cylinder. Contact of the material with the heat-containing or heat-generating surface is achieved by the sandwiching of the support between the drum and guide. Examples of such devices are shown in US. Letters Patent Nos. 3,012,141; 3,242,316; and 3,243,579.

In these devices, whether the guide is moving with the drum or whether there is relative movement, there is contact with both sides of the sheet material to be developed. This means the coating or image-forming substance is at some time in contact with one member of the device. Some of the imageforming substances or coatings which are heat developable are more easily damaged when heated, thus making it desirable to avoid contacting the coated surface during development. Other image-forming sub stances such as powders may be disturbed even when cool which negates the desirability of contact or relative movement between such imaging substances and the developing device.

It is thus an object of the present invention to provide a unit for the heat development of images on various sized backing sheets without requiring contact of the imaging substance with any element of the unit, particularly when the imaging substance is heated.

It is an advantage of the present invention that the area of the support carrying the image-forming substance need not be placed in contact with either a drum or a guide, while affording intimate contact for heat transfer between a heated member and the support material.

Further, the developer unit of the present invention is usable with a wide variety of image-forming materials which, in the presence of heat, develop a permanent image on the support material.

The present invention also provides a unit which is easily used even in dark room conditions as it requires only the insertion of the sheet material into an inlet area and the machine will develop and discharge the material.

The apparatus of the present invention utilizes a cylin- 3,439,905 Patented Apr. 22, 1969 drical, rotatably mounted heated drum formed with tiny surface openings which communicate with manifold means. The manifold means and a source of low positive pressure afford sufficient negative pressure beneath the sheet material so that a force is exerted to hold the same on the surface of the drum throughout a large extent of drum rotation. The manifold and source of positive pressure release the sheet material from the drum during the remaining and lesser extent of drum rotation. The apparatus of the present invention also utilizes fixed guide means spaced from the surface of the drum. The guide means permits the negative pressure to be higher or more nearly atmospheric and yet hold the backing to the drum. The guide means restrict the possibility of removal or displacement of the film or paper support material from the drum while in the apparatus. The guide means contact only an edge of the sheet material (line contact). The guide means do not touch a face or coated surface.

Further, the apparatus is formed with an inlet area and a discharge area. The inlet area has a guide for properly aligning an edge of the sheet material with the drum, which guide, upon the acceptance of the material by pickup rolls and the release of the material by the operator, does not interfere with the material movement through the machine and restricts wrinkling.

The above and further advantages and features of the present invention will become apparent after reading the following description which refers to the accompanying drawing wherein:

FIGURE 1 is a plan view of an apparatus constructed in accordance with the present invention with parts broken away;

FIGURE 2 is a front elevation view of the apparatus of FIGURE 1 with parts broken away to show interior members;

FIGURE 3 is a longitudinal vertical sectional view taken generally along line 33 of FIGURE 1 with some parts broken away; and

FIGURE 4 is a detail view of a manifold.

Referring now to the drawing, the developing unit has a frame 6 comprising a base plate 7 and transversely spaced parallel vertical support plates 8 and 9. A finished housing or casing 11 fits onto the frame 6 to enclose the inner mechnisms. The casing 11 has a front opening or throat 12 permitting insertion of the sheet material to be developed and return of the developed product.

A cylindrical roll 15 is rotatably mounted between the vertical plates 8 and 9. The cylindrical roll 15 has a smooth outer peripheral surface which is formed with a plurality of tiny holes 16. The tiny holes communicate during rotation of the roll with means for subjecting said holes to subatmospheric or negative fluid pressure and positive or above atmospheric fluid pressure during various stages of rotative movement. The structure of the roll may best be understood by reference to FIGURES 2 and 3 which illustrate sections of the roll. The roll 15 comprises a hollow cylindrical core 17, which core has a plurality of axially extending circumferentially spaced flutes or grooves 18 formed in its outer peripheral surface. These grooves 18 form passageways which extend the length of the core when a cylindrical sleeve 19 is placed about and affixed to the core in close fitting engagement with the lands between the grooves thereof in such a manner that the tiny holes in the sleeve align axially with the flutes or grooves. The roll 15 is heated by suitable heating means disposed within the core 17, which means, as illustrated, may be a thin blanket 21 bonded to the inner surface of the core. The blanket 21 may be formed by high-resistance wire sheathed between glass fiber reinforced silicone rubber layers. Automatic temperature control means (not shown) such as heatsensitive means, for example, thermistors or bimetal thermostats may be used to control the temperature of the blanket. The temperature may preferably be controlled by contacts which are controlled by metal bars having a coefficient of thermal expansion which is substantially in the temperature range to which it is subjected in the apparatus of this invention such that changes in the relative length between the core and the bars operate contacts to maintain a substantially constant temperature along the length of the roll. A suitable metal for the bars is an iron nickel alloy having 36% nickel.

The heating circuit to the blanket 21 is provided through slip rings 23 supported by an end cap 24 fitted into one end of the core 17. An end cap 26 is fitted in and supports the opposite end of the core. Each end cap is formed with a plurality of openings 27 extending axially therethrough and aligned with each of the grooves 18 in the core, and the end caps are formed of an insulative material such as a phenolic resin. When the heating circuit is completed by the controls of the machine and/or the temperature sensing means the resistor wires in the blanket increase in temperature and heat is transmitted therefrom to the core and outer shell. Preferably, the heating takes place rapidly when initially turning on the machine to rapidly achieve the desired temperature and quickly prepare the unit for use. A shaft 29 extending through and secured to the end caps support the roll and end caps rotatably in the vertical plates 8 and 9.

Supported from each vertical plate and biased into engagement with the axially outer faces of the end caps 24 and 26 are manifold members 31 and 32 which slidably seal with the outer faces of said end caps. The manifold members are stationarily mounted by means of pins 33 secured to the plates 8 and 9 which extend through openings formed in cars 34 on the manifold. Compression springs 36 are mounted over the pins and engage the ears to press the manifolds against the end caps. Each manifold member is formed with a circular groove 37 in one axial face in opposed relation with the openings 27 in the end caps. This circular groove is divided to form two chambers, one chamber 38 having an extent of about 30 to 45 which is connected through a passageway 39 and conduit 41 to a source of positive pressure and a larger chamber 42 having a circumferential extent of approximately 270 to 315, which latter chamber is connected by a passage 43 and conduit 44 to a source of negative or subatmospheric pressure.

The positive and negative pressures are produced by a unit, generally designated by the reference numeral 45, having a pair of chambers 46 and 47 divided by a partition 48. The partition 48 has an opening 49 therein in which is mounted a fan 51 driven by a motor 52 in a direction to draw air from chamber 46 into chamber 47, creating a negative pressure in chamber 46 and a positive pressure in chamber 47. The amount of negative pressure is controlled by an adjustable inlet valve in chamber 46 formed by relatively movable disks 53 and 53a, each having openings therein, which openings are progressively or incrementally aligned controlling air inflow. A-filter (not shown) is mounted over the plates permitting only filtered air to pass to pressure chamber 47 and into positive pressure manifold 38. The air drawn through the tiny holes 16 and into chamber 46 is filtered by said tiny holes. Manifold chambers 42 of the manifold members 31 and 32 are joined through conduits 44 to a T coupling and by a conduit 55 to chamber 46. Manifold chambers 38 of the members 31 and 32 are joined by conduits 41 to a coupling exhausting outside into the ambient air through an adjustable valve 48 and connected by a conduit 50' to the positive pressure conduits 41 at the T coupling therebetween.

The roll is driven by a suitable drive means including a timing belt drive wheel 54 secured to an extended end of shaft 29 which is joined by a timing belt 54a to a drive wheel 56 of a variable speed electric motor 57.

4 The belt 54a is also directed about a drive wheel 58 which, through a suitable one-way clutch drives a pickup roll 59 which is formed by a shaft and a roll 61 having a plurality of spaced rubber rings 62 encircling the roll and positioned in axially spaced relation along the roll surface. The pickup roll 59 is fixedly mounted in the frame and has associated therewith a smooth surfaced freely rotatable idler roll 63. The pickup roll 59 and the idler roll 63 have slight contact at the nip region between the two to feed the sheet material of various sizes into the machine and into contact with the heated developing roll 15. The reduced pressure in the large chamber 42 of the manifold members 31 and 32 causes negative pressure in the tiny holes 16 to draw the sheet material to the roll and hold the same on the roll. If the sheet material is not very supple, or if it has the stiffness of photographic film (emulsion coated thin sheet of acetate) the negative pressure is not great enough to hold the leading edge of the sheet in contact with the roll so the leading edge engages and is guided about the roll by contact with guide means and transported by the attraction of the same to the roll surface under the forces afforded by the negative pressure in the tiny holes 16 and ambient external pressure. The guide means comprise members 64 which have a crescent shape and which are preferably formed of an insulative material. Guide members 64 are mounted from the support bracket 66 and are so disposed that each guide follows a helical path about the periphery of the cylinder for an extent of more than but less than 270. This helical pattern prevents the guides 64 from serving as heat sinks which could cause a variation in the temperature axially along the cylinder.

As the sheet material is carried about the feed roll the trailing edge of the sheet material will also engage the guide means. The rest of the sheet will conform to the roll surface and no part of the sheet except the leading or trailing edge will engage the guides. As the leading edge of the material is carried into the area where the holes are subjected to the positive pressure the material is lifted from the surface of the roll and will be discharged from the roll and directed outward of the machine over a discharge plate 68. As the film moves out of the machine it again engages the rings 62 of the pickup roll 59 which will move the film out of the machine and out of engagement with roll 15.

The unit illustrated in the drawing also includes guide means for properly positioning a sheet relative to the roll during initial insertion which will permit an operator to guide the material into the machine even while in a dark room situation. It is possible however for the sheet to be slightly bowed or. not absolutely straight when placed in the machine. If one edge is held by a guide it may be possible that the sheet will not straighten out and achieve intimate contact over its entire surface with the roll 15 to achieve uniform development. Therefore it is desirable to release the sheet from any guide after insertion and movement of the sheet by the roll 15. In the apparatus of the present invention this is accomplished by having a fixed guide plate 71, formed with an arcuate shape, mounted adjacent one end of the roll 15 and the idler roll 63. A second spring-biased support plate or shelf 72, having an arcuate configuration corresponding to that of the guide plate 71, is mounted for pivotal movement about the axis of the idler roller. Spring means 73 bias the shelf to a position such that its upper sheet supporting surface is normally flush with the upper surface of the fixed plate 71. When placing a sheet into the machine it is placed on the shelf 72 which is biased downwardly, thus exposing the adjoining edge 74 of the fixed plate. The sheet material may be moved into engagement with edge 74 and aligned therealong while being moved into contact with the pickup roll to be fed into the machine. Upon release of the material by the operator the shelf 72 is raised to a position which is again flush with the fixed plate which also lifts the material out of contact with the guiding edge 74 such that further movement of the sheet material is not subjected to any interference from the fixed guide 71.

The sheet material to be developed in the apparatus of the present invention may include any heat-developable material, for example coatings comprising, silver-halide emulsions, heat-developable diazo emulsions, or other photodhermographic or electrostatic materials. The temperature at which the developing roll may operate is between 100 and 400 P. which is sufiicient for the develop ment of any of these materials. The film is in contact wit-h the roll for about 225 of its rotation. The negative pressure to which the sheet is exposed to hold the sheet to the roll is between 3 inches and 3.5 inches of water and the positive pressure is between 1 inch to 1.5 inches of water. The roll speed adjustment is between 1 and 6 r.p.m.s, which gives a variable development time of between 5 to 38 seconds. Film or paper material having sizes from 5 x 7 inches to 20 x 24 inches may be fed through the machine. The air flow is preferably maintained at about 12 cubic ft. per minute. This air flow is very low and the amount of air movement through the tiny holes (preferably having a diameter of .010 inch on one-quarter inch centers, circumferentially and axially on the roll 15) has a negligable cooling effect. When a large sheet is moved through the machine the air intake through the holes not covered by the sheet is not increased appreciably because of the inlet valve in chamber 46 of the pressure source. Also the negative pressure does not increase upon the tiny holes being covered. The holes 16 are of such small size that they do not cause cool spots on the roll 15 which would cause less heat reaching some spots on the sheet material and uneven development of the image-forming material.

Having thus described the present invention with reference to a preferred embodiment, it will be appreciated that slight modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

1. A developing unit for use in the development of an image, on a support layer of film or paper material by the application of heat to one surface of the material, said unit comprising a frame,

a rotatably mounted roll supported on said frame, said roll comprising a cylindrical sleeve formed with a plurality of tiny openings in the outer cylindrical surface, heating means for heating said sleeve and for substantially maintaining a predetermined even temperature on said sleeve,

manifold means for subjecting said openings to positive and negative pressures upon rotation of said sleeve throughout predetermined extents of rotative movement of said surface about the axis of said sleeve, said extent of negative pressure exceeding the extent of positive pressure,

fixed guide means spaced from said outer cylindrical surface of said sleeve and having an extent less than the peripheral extent of said manifold means affording negative pressure, and

means for rotating said sleeve and for supplying positive and negative pressure to said manifold means.

2. A developing unit according to claim 1 wherein said roll comprises a cylindrical member formed with means defining a plurality of axially extending separate passageways disposed in circumferentially spaced relationship and wherein said tiny openings are formed to communicate with said openings.

3. A developing unit according to claim 2 wherein said manifold means comprise at least one stationary ring member biased into sealing engagement with an end of said roll, said ring member being formed with means defining arcuate grooves affording communication with an open end of said passageways and with means for connecting said grooves with said means for supplying positive and negative pressures.

4. A deVelOping unit according to claim 1 wherein said means for supplying positive and negative pressure to said roll comprises means forming a first and second chamber separated by a partition having an opening therein,

fan means at said opening for drawing air from said first chamber to said second chamber,

means defining an adjustable inlet opening into said first chamber, and

conduit means connected between said manifold means and each of said first chamber and said second chamber for applying, respectively, a negative and positive pressure thereto.

5. Sheet guide means for use at the entrance opening of a sheet-handling machine, said guide means comprising in combination a fixed guide plate supported stationarily with one vertical edge thereof depending from an upper surface thereof and in a predetermined reference position with relation to a said machine,

a support plate having a sheet-supporting surface and mounted in juxtaposition to said guide plate,

means for p-ivotally supporting said support plate for movement about an axis normal to said vertical edge from a normal position with the sheet-supporting surface aligned with said upper surface of said guide plate to a depressed position exposing said one vertical edge of said guide plate, and

means for biasing said support plate to said normal position.

6. Sheet guide means according to claim 5 wherein said upper surface and said sheet-supporting surface are each curved uniformly in one direction and are straight in the direction normal to said vertical edge.

7. Sheet guide means according to claim 5 wherein feed roller means are positioned along one edge of said support plate, with one roller rotatable about the pivot axis of said support plate, for receiving and drawing a sheet off said sheet-supporting surface into a said machine.

8. An image-developing unit for developing an image by heat on a surface of a sheet-like support by cont-acting only one surface of said support with heat, said unit comprising:

a casing and frame forming an enclosure and including means defining an inlet and outlet opening for insertion and discharge of sheet material,

a rotatably mounted cylindrical roll supported within said enclosure, said roll comprising a cylindrical sleeve formed with a plurality of tiny openings in the outer cylindrical surface, manifold means for subjecting said openings to low positive and negative pressures as said roll is rotated about its axis, heating means for heating the outer cylindrical surface of said roll substantially uniformly, said negative pressure at said tiny openings affording means to hold one surface of a sheet in intimate contact with 'said heated cylindrical surface and said rotatable roll advancing a said sheet from said inlet opening to said outlet opening,

guide means at said inlet opening for aligning a said sheet with said roll to afford intimate contact with the surface of said roll, said guide means comprising a fixed plate having a vertical edge positioned in a plane perpendicular to the axis of said roll at a position between the ends of said roll, a support plate pivoted on an axis parallel to the axis of said roll and normal to said vertical edge and juxtapositioned to said fixed plate adjacent said vertical edge, said support plate having a sheet-supporting surface aligned with said fixed plate in a normal position and a depressed position exposing said vertical edge, biasing means for urging said support plate to said normal position and permitting movement of said support plate to said depressed position, whereby an operator can align a said sheet with said vertical edge upon insertion of the sheet into the unit for contact with said roll and upon release of the sheet 5 said edge will not interfere with the movement of said sheet by return of the support plate to said normal position.

8 References Cited JOHN J. CAMBY, Primary Examiner.

US. Cl. X.R. 346-76 

